Search Results (1,025)

Anthropogenic barriers fragment Portuguese rivers, threatening endemic freshwater fish communities. This study compiled national inventories and peer-reviewed research (2002–2024) to quantify fishway implementation, evolution and typology, while evaluating fish performance from published research. One hundred fishways built between 1950 and 2024 were recorded, half of which were constructed after the implementation of the Water Framework Directive in Portugal (29 Dec 2005), tripling the annual construction rate. Fishways were found to be associated mainly with weirs (46%) and small hydropower plants (44%), with typology being dominated by the pool-type design (67%), nature-like facilities (18%), fish locks and combined systems (6% each), fish lifts (2%) and a single eel pass. Forty scientific contributions addressed fishway effectiveness; three-quarters dealt with pool-type facilities, while 12.5% and 10% focused on nature-like fishways and lifts, respectively. Experimental and field studies highlighted species-specific hydraulic preferences, the benefits of vertical slot and multislot configurations, and the potential of retrofitting fishways with macro-rugosities (i.e., fixed structural elements placed on the bottom) to improve non-salmonid fish passage. However, low attraction efficiency, limited multi-season monitoring and risks of aiding invasive species remain a concern. Research needs are proposed, including the refinement of species-specific hydrodynamic criteria, and the development of standardized efficiency metrics and of selective passage solutions, to advance fishway performance under Mediterranean hydrological constraints. Full article

The Nile tilapia (Oreochromis niloticus), a key aquaculture species, displays marked sexual growth dimorphism, with males growing faster than females. This process is governed by intricate interactions between antagonistic regulators, including transcription factors, growth factors, and steroid hormones, operating through sex-specific developmental pathways. While circular RNAs (circRNAs) are known to modulate gene expression by sponging microRNAs (miRNAs), their role in teleost sex differentiation remains poorly understood. To address this gap, we profiled circRNA expression in tilapia gonads by constructing six circRNA libraries from testes and ovaries of 180 days after hatching (dah) fish, followed by high-throughput sequencing. We identified 6564 gonadal circRNAs distributed across all 22 linkage groups, including 226 differentially expressed circRNAs (DECs; 108 testis-biased, 118 ovary-biased). Functional enrichment analysis linked their host genes to critical pathways such as cAMP signaling, cell adhesion molecules, and—notably—sexual differentiation processes (e.g., estrogen signaling, oocyte meiosis, and steroid hormone biosynthesis). Furthermore, we deciphered competing endogenous RNA (ceRNA) networks, uncovering circRNA–miRNA–mRNA interactions targeting germ cell determinants, sex-specific transcription factors, and steroidogenic enzymes. This study provides the first systematic exploration of circRNA involvement in tilapia sex differentiation and gonadal differentiation, offering novel insights into the post-transcriptional regulation of sexual dimorphism. Our findings advance the understanding of circRNA biology in fish and establish a framework for future studies on aquaculture species with similar reproductive strategies. Full article

Land degradation in Iraq’s Mesopotamian plain threatens food security and rural livelihoods, yet the relative roles of climatic water deficits versus anthropogenic pressures remain poorly attributed in space. We test the hypothesis that multi-timescale climatic water deficits (SPEI-03/-06/-12) exert a stronger effect on vegetation degradation risk than anthropogenic pressures, conditional on hydrological connectivity and irrigation. Using Babil and Al-Qadisiyah (2000–2023) as a case, we implement a four-part pipeline: (i) Fractional Vegetation Cover with Mann–Kendall/Sen’s slope to quantify greening/browning trends; (ii) LandTrendr to extract disturbance timing and magnitude; (iii) annual LULC maps from a Random Forest classifier to resolve transitions; and (iv) an XGBoost classifier to map degradation risk and attribute climate vs. anthropogenic influence via drop-group permutation (ΔAUC), grouped SHAP shares, and leave-group-out ablation, all under spatial block cross-validation. Driver attribution shows mid-term and short-term drought (SPEI-06, SPEI-03) as the strongest predictors, and conditional permutation yields a larger average AUC loss for the climate block than for the anthropogenic block, while grouped SHAP shares are comparable between the two, and ablation suggests a neutral to weak anthropogenic edge. The XGBoost model attains AUC = 0.884 (test) and maps 9.7% of the area as high risk (>0.70), concentrated away from perennial water bodies. Over 2000–2023, LULC change indicates CA +515 km², HO +129 km², UL +70 km², BL −697 km², WB −16.7 km². Trend analysis shows recovery across 51.5% of the landscape (+29.6% dec⁻¹ median) and severe decline over 2.5% (−22.0% dec⁻¹). The integrated design couples trend mapping with driver attribution, clarifying how compounded climatic stress and intensive land use shape contemporary desertification risk and providing spatial priorities for restoration and adaptive water management. Full article

Multiple unmanned aerial vehicle (UAV) systems have attracted considerable research interest due to their broad applications, such as formation control. However, decentralized UAV formation faces challenges stemming from limited local observations, which may lead to consistency conflicts, and excessive communication. To address these issues, this paper proposes SemanticBC-DecAF, a decentralized adaptive formation (DecAF) framework under a leader–follower architecture, incorporating a semantic broadcast communication (SemanticBC) mechanism. The framework consists of three modules: (1) a proximal policy optimization (PPO)-based semantic broadcast module, where the leader UAV transmits semantically encoded global obstacle images to followers to enhance their perception; (2) a YOLOv5-based detection and position estimation module, enabling followers to infer obstacle locations from recovered images; and (3) a multi-agent proximal policy optimization (MAPPO)-based formation module, which fuses global and local observations to achieve adaptive formation and obstacle avoidance. Experiments in the multi-agent simulation environment MPE show that the proposed framework significantly improves global perception and formation efficiency compared with methods that rely on local observations. Full article

Electrochemical water splitting has emerged as a pivotal strategy for advancing sustainable and renewable energy technologies. However, its practical deployment is often hampered by sluggish reaction kinetics, large overpotentials, and the high cost of efficient electrocatalysts. To overcome these critical challenges, a novel bifunctional electrocatalyst based on electropolymerized CeO₂-NiO with polyacrylic acid (Ce-Ni-PAA) has been rationally engineered for overall water splitting. The strategic incorporation of conductive polymer framework enables effective modulation of the local electronic structure, enhances charge transport pathways, and maximizes the density of electrochemically accessible active sites, thereby substantially boosting catalytic performance. When evaluated in a 1 M KOH alkaline medium, the optimized Ce-Ni-PAA_0.5/NF hybrid demonstrates remarkable catalytic activity with 366.5 mV overpotential at 50 mA cm⁻², coupled with lower Tafel slope of 93.5 mV dec⁻¹. Additionally, the Ce-Ni-PAA_0.5/NF electrocatalyst exhibits exceptional ECSA of 1092.3 cm², which confirms the presence of a significantly larger number of electrochemically active sites. The electrocatalyst retains its performance even after 5000 continuous cycles of operation. The superior performance is attributed to the synergistic effects arising from the enriched composition, efficient electron transport channels, and abundant catalytic centers. Collectively, this study not only highlights the significance of rational structural and compositional design but also offers valuable insights toward the development of next-generation, cost-effective bifunctional electrocatalysts with strong potential for scalable water splitting and clean energy applications. Full article

The presence of discontinuities in fractured reservoirs, their mechanical and physical characteristics, and fluid flow through them are important factors influencing their effective large-scale properties. In this paper, the variation of elastic moduli in a block measuring 100 × 100 × 100 m³ that hosts a discrete fracture network (DFN) is evaluated using the discrete element method (DEM). Fractures are characterised by (1) constant, (2) interlocked, and (3) mismatched stiffness properties. First, three uniaxial verification tests were performed on a block (1 × 1 × 2 m³) containing a circular finite fracture (diameter = 0.5 m) to validate the developed numerical algorithm that implements the three fracture stiffnesses mentioned above. The validated algorithms were generalised to fractures in a DFN embedded in a 100 × 100 × 100 m³ rock block that reproduces in situ conditions at various depths (4.7 km, 2.3 km, and 0.5 km) of the Soultz-sous-Forêts geothermal site. The effective elastic moduli of this large-scale rock mass were then numerically evaluated through a triaxial loading scenario by comparing to the numerically evaluated stress field using the DFN, with the stress field computed using an effective homogeneous elastic block. Based on the results obtained, we evaluate the influence of fracture interaction and stress perturbation around fractures on the effective elastic moduli and subsequently on the large-scale P-wave velocity. The numerical results differ from the elastic moduli of the rock matrix at higher fracture densities, unlike the other methods. Additionally, the effect of nonlinear fracture stiffness is reduced by increasing the depth or stress level in both the numerical and semi-analytical methods. Full article

This work introduces the Reverse Steam Rising Process (RSRP), a novel dissolution method, for the preparation of highly homogeneous organo-nickel composites. This approach enables gradual material dissolution, resulting in improved material integration. We investigate two distinct synthetic pathways: a direct organic material–nickel composite and a surfactant-assisted variation. Our findings demonstrate that the inclusion of a surfactant significantly improves the properties of the resulting organo-nickel composite. The RSRP method differs from traditional synthesis methods in that it utilizes reverse steam condensation to create a highly porous, multi-level structure. This unique structure significantly boosts the material’s electrocatalytic performance, particularly for the oxygen evolution reaction (OER). The Ni-MOF-CTAB catalyst exhibits an overpotential of 397 mV at 10 mA cm⁻² and a Tafel slope of 183 mV dec⁻¹, outperforming pristine Ni-MOF. The hierarchical design promotes superior ion and gas transport, while the distinctive organometallic configuration optimizes electronic interactions critical for OER activity. This innovative process enables precise control over both the micro- and nanoscale morphology of the nickel-based catalyst, ultimately leading to superior performance metrics. This advancement offers a new pathway for developing high-performance nickel organometallic materials for diverse electrocatalytic applications. Full article

Digital Entrepreneurial Capability (DEC) is the integrated and learnable capacity that equips individuals, or founding teams, to sense, evaluate, and exploit entrepreneurial opportunities within digitally intermediated, platform-centric markets. The construct synthesises four interlocking elements. First, it requires technical dexterity: mastery of data engineering, AI-driven analytics, low-code development, cloud orchestration, and cybersecurity safeguards. Second, it draws on accumulated human capital—formal education, sector experience, and tacit managerial know-how that ground vision in operational reality. Third, DEC hinges on an opportunity-seeking mindset characterised by cognitive alertness, creative problem framing, a high need for achievement, and autonomous motivation. Finally, it depends on calculated risk tolerance, encompassing the ability to price and mitigate economic, technical, algorithmic, and competitive uncertainties endemic to platform economies. When these pillars operate synergistically, entrepreneurs translate digital affordances into scalable, resilient business models; when one pillar is weak, capability bottlenecks arise and ventures falter. Because each pillar can be intentionally developed through education, deliberate practice, and ecosystem support, DEC serves as a practical roadmap for stakeholders. It now informs scholarship across entrepreneurship, information systems, innovation management, and public-policy disciplines, and guides interventions ranging from curriculum design and accelerator programming to due-diligence heuristics and national digital literacy initiatives. Full article

The zeolite structure, with its precisely distinct pores, settled cages, and adsorption sites, enables the formation and stabilization of isolated metal centers. These well-defined structures make metal-loaded zeolites promising catalysts. Three different β zeolites were synthesized by an aqueous ion-exchange procedure, firstly with cobalt (Co), and secondly with zinc (Zn), cerium (Ce), and copper (Cu), to make three bimetallic CoZn/β, CoCe/β, and CoCu/β zeolites, respectively. X-ray powder diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, and low-temperature nitrogen adsorption analysis revealed the structural, morphological, and surface properties of the studied materials, while optical properties were investigated by UV-Vis diffuse reflectance spectroscopy. The lowest onset potential of 1.67 V was obtained for both CoZn/β and CoCe/β, while the somewhat positive value of 1.70 V was observed for CoCu/β. CoZn/β exhibited the lowest value of Tafel slope of 89 mV dec^−1, while slightly higher values of 109 and 113 mV dec⁻¹ were calculated for CoCe/β and CoCu/β during ORR, respectively. CoZn/β showed four-electron pathways of ORR, CoCu/β showed a mixed ORR mechanism, while CoCe/β offered two-electron pathways of ORR. All presented results established that CoZn/β had the highest OER/ORR activity, followed by CoCu/β, while CoCe/β had the lowest activity detected. Full article

Against the background of the accelerating global transition towards a low-carbon energy system, the lithium-ion battery (LIB) industry has witnessed a rapid development. Concurrently, fire accidents in LIB application scenarios have occurred frequently, with safety issues becoming increasingly prominent. Thermal runaway of LIBs is the direct cause of such fires. During the thermal runaway process of LIBs, lithium salts in the electrolyte undergo thermal decomposition reactions with carbonate-based electrolytes, releasing a large amount of heat and fire gases. Among them, the thermal decomposition reactions of LiPF₆ with electrolytes are coupled and superimposed, exhibiting a significant synergistic effect. This paper employs quantum chemical calculation methods to investigate the thermal decomposition reaction mechanisms between PF₅ and POF₃, which generated from the thermal decomposition of LiPF₆ and carbonate-based electrolytes (EC, DMC, and DEC) during the thermal runaway process of LIBs; and presents detailed chemical reaction mechanism models. The P atoms in PF₅ or POF₃ combine with the O atoms of the ether oxygen groups in carbonates, while the F atoms combine with the C atoms adjacent to the ether oxygen groups. This promotes the ring-opening or chain scission of carbonate molecules, reduces the energy required for the reaction, and accelerates the thermal decomposition reaction and the generation of fire gases. Modification of EC, DMC, and DEC through fluorination can effectively inhibit the catalytic effect of PF₅ and POF₃ and improve the oxidation resistance and thermal stability of the electrolytes. Full article

Currently, the growing demand for sustainable hydrogen makes the oxygen evolution reaction (OER) increasingly important. To boost the performance of electrochemical cells for water electrolysis, both cathodic and anodic sides need to be optimized. Noble metal catalysts for the OER suffer from high costs and limited availability; therefore, developing efficient, low-cost alternatives is crucial. This work investigates manganese-based materials as potential noble-metal-free catalysts. Mn antimonates, Mn chlorates, and Mn bromates were synthesized using ultrasound-assisted techniques to enhance phase composition and homogeneity. Physicochemical characterizations were performed using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), together with energy-dispersive X-ray spectroscopy (EDX) and surface area analyses. All samples exhibited a low surface area and inter-particle porosity within mixed crystalline phases. Among the catalysts, Mn_7.5O₁₀Br₃, synthesized via ultrasound homogenization (30 min at 59 kHz) and calcined at 250 °C, showed the highest OER activity. Drop-casted on Fluorine-Doped Tin Oxide (FTO)-coated Ti mesh, it achieved an overpotential of 153 mV at 10 mA cm⁻², with Tafel slopes of 103 mV dec⁻¹ and 160 mV dec⁻¹ at 1, 2, and 4 mA cm⁻² and 6, 8, 10, and 11 mA cm⁻², respectively. It also demonstrated good short-term stability (1 h) in acidic media, with a strong signal-to-noise ratio. Its short-term stability is comparable to that of the benchmark IrO₂, with a potential drift of 15 mV h⁻¹ and a standard deviation of 3 mV for the best-performing electrode. The presence of multiple phases suggests room for further optimization. Overall, this study provides a practical route for designing noble metal-free Mn-based OER catalysts. Full article

Uncertainty remains a central challenge in robotic navigation, exploration, and coordination. This paper examines how Partially Observable Markov Decision Processes (POMDPs) and their decentralized variants (Dec-POMDPs) provide a rigorous foundation for decision-making under partial observability across tasks such as Active Simultaneous Localization and Mapping (A-SLAM), adaptive informative path planning, and multi-robot coordination. We review recent advances that integrate deep reinforcement learning (DRL) with POMDP formulations, highlighting improvements in scalability and adaptability as well as unresolved challenges of robustness, interpretability, and sim-to-real transfer. To complement learning-driven methods, we discuss emerging strategies that embed probabilistic reasoning directly into navigation, including belief-space planning, distributionally robust control formulations, and probabilistic graph models such as enhanced probabilistic roadmaps (PRMs) and Canadian Traveler Problem-based roadmaps. These approaches collectively demonstrate that uncertainty can be managed more effectively by coupling structured inference with data-driven adaptation. The survey concludes by outlining future research directions, emphasizing hybrid learning–planning architectures, neuro-symbolic reasoning, and socially aware navigation frameworks as critical steps toward resilient, transparent, and human-centered autonomy. Full article

In alkaline water electrolysis, conventional polymer binders like Nafion suffer from poor hydroxide conductivity and inadequate interfacial properties. Herein, a thermally cyclized polyacrylonitrile (CPAN) binder system with a conjugated ladder structure is introduced. The CPAN binders are synthesized by controlled thermal treatment under various temperatures, among which CPAN-400 demonstrates the optimal 57.03% pyridinic N content, provides π-conjugated pathways for enhanced electronic conductivity, and indicates hierarchically porous electrode architectures. The NiFe/CPAN-400 electrode achieves enhanced oxygen evolution performance with an overpotential of 354 mV at 100 mA cm⁻², which is 153 mV and 103 mV lower than NiFe–Nafion and NiFe–PAN, respectively. This enhancement results from synergistic effects, including an electrochemically active surface area increased 2.3-fold, improved electrolyte wettability, and optimized charge transfer kinetics. The pyridinic nitrogen-enriched structure also facilitates a rate-determining step transition from charge transfer to *OOH formation, with a Tafel slope of 59.9 mV dec⁻¹. This work establishes thermally induced polymer cyclization as a versatile strategy for advanced binder developments. Full article

Automated vehicles (AVs) are expected to shape the future of transportation and to improve traffic flow and safety. Studies have focused on AVs effects on traffic flow during the transition to full automation, with few examining their influence on human-driven vehicles (HDVs). This study investigated potential changes in HDVs’ driving behavior induced by the presence of AVs with different driving styles (aggressive vs. cautious) at varying market penetration rates (MPRs) (0%, 25%, 50%, and 75%). First, a driving simulator experiment with 160 people (56 females, 104 males) was conducted to collect HDV trajectory data. Then, a microsimulation model was implemented in VISSIM, where HDV behavioral parameters were calibrated using the driving simulator data. Average time headway (THW), relative velocity (RelVel), average acceleration (Acc), average deceleration (Dec), and lane change frequency (LnCh) were used as behavioral metrics. A two-way ANOVA was applied for analysis. Results showed that higher AVs’ MPRs decreased THW, Acc, and Dec in HDVs, while RelVel increased with cautious AVs and decreased with aggressive AVs. Similar trends were observed for LnCh. These findings highlight the need to consider potential HDVs behavioral adaptation during the transition phase, as neglecting it may lead to inaccurate traffic assessments and ineffective policies. Full article

Among various H₂ production methods, splitting water using renewable electricity for H₂ production is regarded as a promising approach due to its high efficiency and zero carbon emissions. The oxygen evolution reaction (OER) is an important part of splitting water, but also the main bottleneck. The anodic oxygen evolution reaction (OER) for water electrolysis technology involves multi-electron/proton transfer and has sluggish reaction kinetics, which is the key obstacle to the overall efficiency of electrolyzing water. Therefore, it is necessary to develop highly efficient and cheap OER electrocatalysts to drive overall water splitting. Herein, a series of efficient RuO₂-Co₃O₄ composites were synthesized via a straightforward three-step process comprising solvothermal synthesis, ion exchange, and calcination. The results indicate that using 10 mg of RuCl₃·xH₂O and 15 mg of Co-MOF precursor in the second ion exchange step is the most effective way to acquire the Co₃O₄-RuO₂-10 (RCO-10) composite with the largest specific area and the best electrocatalytic performance after the calcination process. The optimal Co₃O₄-RuO₂-10 composite powder catalyst displays low overpotential (η₁₀ = 272 mV), a small Tafel slope (64.64 mV dec⁻¹), and good electrochemical stability in alkaline electrolyte; the overall performance of Co₃O₄-RuO₂-10 surpasses that of many related cobalt-based oxide catalysts. Furthermore, through integration with a carbon cloth substrate, Co₃O₄-RuO₂-10/CC can be directly used as a self-supporting electrode with high stability. This work presents a straightforward method to design Co₃O₄-RuO₂ composite array catalysts for high-performance electrocatalytic OER performance. Full article